Depth measuring apparatus



Ofi 24, 1944. M. SCHLUMBERGER DEPTH MEASURING APPARATUS Original Filed Aug. 20, 1938 Fl j.

v INVENToR. #f1/Pea @au wmf/96H? Patented ct. 24, 1944 UN ITE ils- TTES rsu

Marcel Schlumberger,

assignments, to Schlumberl Corporation, a corporation oil Delaware assignor, by mesne ger Well Surveying Houston, Tex.,

oiiginsl appueauon August zo, 193s, serial No.

225,951, now Patent No.

ber 19, 1943.

2,332,348, dated Octo- Divided and this application December 29, 1942, Serial No. 470,447. In France June 28, 1938 7 claim. (ci. sai-126.5)

The present invention relates to apparatus for determining depths, and more particularly to improved apparatus for accurately determining distances in a bore hole from a given reference point therein.

' This application is a division of my copending application for Method and device for referring a level in a bore hole to the bottom of said bore hole, Serial No. 225,951, filed August 20, 1938, now patent number 2,332,348, dated Oct 19, 1943.

In the present practice, the depth of a bore hole is usually determined by lowering a plummet on a cable to the bottom of the bore hole, and measuring either the length of cable paid out or the length of cable taken up in raising the plummet to the surface. Likewise, where the bore hole depth is known, and it is desired to locate apparatus such as a gun perforator in the bore hole at a given distance from the top' or bottom thereof, this is often accomplished by lowering the apparatus on a cable to the bottom of -the bore hole and taking up. a length of cable equal-to the distance of the desired location from the bottom of the bore hole.

These methods, however, have been found to be generally unsatisfactory because of the diiiiculty involved in determining the exact moment when the plummet engages or leaves the bottom of the bore hole. i

An object of the present invention, accordingly, is to provide improved apparatus for determining depths in a bore hole in which a signal is initiated at the instant the plummet leaves its initial position in the bore hole, thus enabling depth measurements to be made with great accuracy.

Another object of the invention is to provide improved signalling apparatus for mechanically initiating a signal when the plummet engages or leaves the bottom of the bore hole.

Additional objects and advantages of the invention will appear from the following detailed description of a representative embodiment taken in connection with the accompanying drawing, in which:

Figure 1 is a schematic diagram of apparatus constructed according to the invention, shown in operative position in an uncased bore hole;

Figure 2 is a, schematic diagram showing the apparatus of Figure 1 in position in a cased bore hole;

Figure 3 is an enlarged view in longitudinal section illustrating in detail the signalling apparatus shown in Figures 1 and 2, and

Figure 4 is a partial view illustrating a further modification of the apparatus shown in Figure 2.

Referring now to Figure 1, sounding apparatus I constructed according to one invention is type, at the lower end of containing a'column of conducting liquid I2. As shown in greater detail in Figure 3, the apparatus I0 may comprise a plummet I3 of any suitable which is mounted a cylndrlcal casing I4 within which are disposed two spaced apart switch contacts I5 and I6. The upper switch contact I6 is connected to an insulated conductor I1 in the supporting cable, the uppenend of which is connected in seriesv with one terminal of amr suitable means for indicating an interruption of the ow of current in the circuit, such as for example, a conventional milliammeter I8. 'I'he other terminal of the milliammeter I8 is connected to one terminal of a suitable source of electrical energy I9, the other terminal of which is grounded at the point 20 at the surface ofthe earth. I

The lower switch contact l5 in the'casing I4 is secured to a piston member ZI which is slidably mounted within the casing I4.- Secured to the lower end of the piston 2| is" an actuator member 22 which extends through an aperture 23 .in the lower wall of the casing I4 and which terminates in a laterally extending member 24. The switch contacts I5 and I6 are normally maintained open by means of a suitable biasing spring 25, the upper end of which' engages the lower face of the casing I4 and the lower end of which engages tle upper surface of the laterally extending member 25. The switch contacts I5 andv I 6 are enclosed within a sleeve 26 made of resilient material such as rubber, for example, forming a chamber which is illled with an insulating liquid.

If, for example, it is desired to determine the depth of the bore hole `II with the apparatus described above, the apparatus I0 is lowered into the bore hole II until the laterally extending member 24 engages the bottom 21 thereof. So long as the laterally extending member 24 on the actuator member 22 does not engage a solid object, the switch contacts I5 and I6 are maintained out of engagement by the biasing spring 25. However, as soon as the laterally extending member 24 engages the bottom 2l of the bore hole II, the actuator member 22 is forced upwardly against the compression in the spring 25 until the contacts I5 and I6 are in engagement.

The engagement of the switch contacts I5 and I6 closes an electrical circuit including the source o f electrical energy I9, the milliammeter I8, the single conductor I1 in the supporting cable, the engaged switch contacts I5 and I6, the piston 2|, the casing I4, the conducting bore hole liquid I2 the borehole.

Inasmuch as the supporting cable is elastic,

it tends to stretch, so that the apparatus I does not immediately leave the bottom 21 of the bore hole I0. When the apparatus finally moves from its rest position, the spring 25l causes the switch contacts I5 and I6 to separate, breaking the electrical circuit. The interruption of the ow of current in the circuit is indicated by the milliammeter I 8, providirg a signal at the surface that the apparatus I0 has begun to move. From the instant the signal is received, the length of cable pulled up in raising the apparatus I0 to the surface of the earth is measured. Since the initial elastic elongation of the cable is eliminated from the measurement, this length, for all practical purposes, is equal to the depth of the bore hole II.

In the mode of operation illustrated in Figure 2 of the drawing, the bore hole I I is provided with a metallic casing 28, the bottom of which may be-closed olli in the conventional manner by means of a cement plug 29. If the bore hole I I contains a column of conducting liquid I2, the manner of operation is exactly the same as described above in connection with Figures l and 3. If, however, the liquid I2 is non-conducting or, if there is no liquid at all in the bore hole II, the circuit may be closed by direct contact between the casing 28 and the apparatus I0. This may be accomplished for example, by mounting a conventional type wire brush 30, such,as is disclosed in prior Patent No. 2,233,420 on the cylindrical casing I4, as shown in Figure 2.

If desired, the upper end of the conductor I1 may be directly connected to the casing 28 at the point 3|, as shown in Figure 4.

Where bore hole apparatus, such as `a gun perforator, for example, constitutes the plummet I3, and it is desired to locate such apparatus at a predetermined distance from the bottom of the bore hole I0, essentially the same procedure is followed. The 'only difference is that, after the signal is received at the surface, a length of the cable equal to the predetermined distance is pulled up, thereby positioning the apparatus at the desired level. l

It will be understood from the foregoing description that the invention provides new and improved apparatus for providing a signal at the surface of the earth at the instant a sounding plummet leaves an initial point of reference such as, for example, the bottom of a bore hole. It thus enables depth measurements to be obtained in which errors produced by the elastic elongation of the supporting cable may be minimized.

In the foregoing description, the term plummet has been used to designate the load supported by the cable. It is to be understood that this load or plummet may be of any desired type and may be made of any suitable material. It is only necessary that it be heavy venough to insure that the cable will reach the bottom of Specifically, the plummet may comprisey any apparatus used in Ybore hole operations such as, for example, a gun perforator.

' While a specific embodiment has been described and grounded at the surface of the earth, a.

source of electrical energy for energizing the circuit including said conductor, means responsive to the current flow in said circuit, and an actuator for said switching means, said actuator extending downwardly from the frame and being adapted to operate said switching meanswhen it engages a solid object. i

2. In an electric sounding apparatus foruse in cased wells of considerable depth, a sounding weight adapted to be lowered into the metallic casing of the well; make-and-break electric switch means carried by said weight; a sounding line secured to said weight and comprising a single, insulated conductor connected in circuit with one side of said switch means, the other side thereof having an electrical connection through the said weight presenting an exposed contact on its outside adapted to be placed in circuit with the metallic casing; and means projecting outwardly from and movably associated with the said weight and constructed and arranged to operate the switch means whensaid projecting means encounters a solid object in the well.

3. In a system for electrically sounding oil wells having a metallic casing extending substantially throughout the depth thereof, the combination comprising a sounding weight adapted to be lowered into the metallic casing of the well; a make-and-break electric switch within said weight; a weight line consisting of a single insulated conductor connected at one end to one terminal of said switch, the other terminal of said switch having an electrical connection through said weight presenting an exposed contact on the outside of said weight adapted to be placed in circuit with the adjacent portion of the metallic casing; a switch-operating member projecting from said weight and movable with respect thereto constructedV and arranged to operate the switch upon encounter with a solid object within the well casing; and current flow indicating means connected in circuit with the other end portion of the weight line conductor and the surface end of the metallic casing.

4. A sounding weight for use in oil wells or the like comprising electric switching means; conductors operatively associated with said switching means for controlling a source of current; a liquid-filled chamber in said weight containing said switching means; and means partially projecting from and slidably associated with the weight and arranged for opening and closing said switching means when slid by being brought into contact with an external object, said switch operating means having opposed portions arranged to be exposed to approximately the same hydrostatic pressure in the well or the like so as to counteract the tendency of the switch operating means to move in response to hydrostatic pressure on the part thereof which projects from the weight for engagement with an external object.

5. In depth determining apparatus, a signalling device comprising a body adapted to belowered in a bore hole, said body having a chamber portion therein terminating in an opening at the lower extremity thereof, a contact member secured in the body and extending into the chamber, a movable member in the chamber having a contact thereon, both said contacts being enclosed within a exible casing, and an actuator on the movable member and extending through the opening in the body for closing the contacts.

6. In depth determining apparatus, a signalling device comprising a body adapted to belowered in a bore hole, said body having a chamber portion therein terminating in an opening at the lower extremity thereof, conductive means in the upper portion of said body, extending downwardly into the chamber and terminating in a contact element, a movable member in the lower` portion of said chamber having an upwardly projecting portion terminating in a contact element, said conductive means and upwardly projecting Portion being connected by a tightly tted flexible enclosure containing an insulating liquid within which the said contact elements are disposed, said movable member having a portion extending downwardly through the opening in the body, and terminating in a laterally extended portion, and resilient means disposed between the body and said laterally extended portion for maintaining the contacts normally disengaged.

7. In depth determining apparatus, the combination of a body adapted to be lowered in a bore hole, said body having a chamber portion therein terminating in an opening at the lower extremity thereof, a contact member non-conductively secured in the body and extending into the chamber, a movable member in the chamber having a contact thereon, both said contacts being enclosed within a exible casing containing insulating liquid, means extending through the opening in the body for actuating said movable member to close the contacts, resilient means associated with said actuating means for maintaining the contacts normally disengaged, an insulated conductor connected at one end to said rst contact, its other end being grounded, a source of voltage in the circuit of said conductor, and current actuated means in said last named circuit for indicating whether said contacts are engaged or disengaged.

MARCEL SCHLUMBERGER. 

